The following proposal is designed to retain individuals as donors once they have entered the voluntary blood donation system and to increase the frequency of their donations. The specific aims of the proposed study are: (1) to identify significant factors influencing regular blood donations by individuals with different donation histories - first-time, second-time, committed (frequent), and lapsed donors; (2) to develop and assess the validity of behavioral models to increase donor retention and to predict whether first and second time donors will contribute again; (3) to develop donor-retention interventions, especially for the first and second time donors; and (4) to identify homogeneous subgroups among first, second and committed donors who may be receptive to different types of intervention strategies to increase the frequency of their donations; (5) to evaluate the success of cost-effectiveness of the new interventions compared to existing blood center maintenance strategies; and (6) to identify whether or not donors have a limit or ceiling on how often they will donate per year. We propose to draw on two related social psychological theories to combine cognitive and behavioral approaches to blood donor retention and to use the findings to construct a multiattribute model of donor decision-making. A behavioral decision model will be used to predict donor behavior prospectively and to target and direct the design of interventions to increase donor retention and the frequency of donations.